Field of the Invention
The invention relates to a power supply system and a control method therefor.
Description of the Related Art
Conventional converter-controlled power supply systems cannot improve or enhance stability of the power systems. Stabilization capability refers to the ability of a device to enhance the stability of a system or other devices. Specifically, these power supply systems without inertia cannot provide synchronous torque in the power systems. Therefore, to replace synchronous motors with the converter-controlled power supply systems is unfavorable for stability of the power systems.
People have concerns about instability of the power systems caused by unconventional converter-controlled power supply systems, and some have proposed methods for inertial control, all of which have a feature in common, namely preset values of electromagnetic power or electromagnetic torque according to measured frequencies of the power systems, and thus output power of generators are varied, so that some functions of the synchronous motors are simulated. In details, as shown in FIG. 1, firstly a frequency of the power system is measured so as to obtain a change rate thereof, then a control instruction for the electromagnetic power or the electromagnetic torque is generated based on the change rate, which forces a rotation speed of the synchronous motor to change whereby releasing mechanical energy stored therein.
Although the above-mentioned methods are quite straightforward, it is required to measure the frequencies of the power systems, resulting in increase in control loops and cost, and certain unwanted impact on the generators by the control loops in operation.